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2024-01-31x86/entry: Add fred_entry_from_kvm() for VMX to handle IRQ/NMIXin Li
In IRQ/NMI induced VM exits, KVM VMX needs to execute the respective handlers, which requires the software to create a FRED stack frame, and use it to invoke the handlers. Add fred_irq_entry_from_kvm() for this job. Export fred_entry_from_kvm() because VMX can be compiled as a module. Suggested-by: Sean Christopherson <seanjc@google.com> Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Xin Li <xin3.li@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Tested-by: Shan Kang <shan.kang@intel.com> Link: https://lore.kernel.org/r/20231205105030.8698-32-xin3.li@intel.com
2024-01-31x86/fred: Fixup fault on ERETU by jumping to fred_entrypoint_userXin Li
If the stack frame contains an invalid user context (e.g. due to invalid SS, a non-canonical RIP, etc.) the ERETU instruction will trap (#SS or #GP). From a Linux point of view, this really should be considered a user space failure, so use the standard fault fixup mechanism to intercept the fault, fix up the exception frame, and redirect execution to fred_entrypoint_user. The end result is that it appears just as if the hardware had taken the exception immediately after completing the transition to user space. Suggested-by: H. Peter Anvin (Intel) <hpa@zytor.com> Signed-off-by: Xin Li <xin3.li@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Tested-by: Shan Kang <shan.kang@intel.com> Link: https://lore.kernel.org/r/20231205105030.8698-30-xin3.li@intel.com
2024-01-31x86/fred: Let ret_from_fork_asm() jmp to asm_fred_exit_user when FRED is enabledH. Peter Anvin (Intel)
Let ret_from_fork_asm() jmp to asm_fred_exit_user when FRED is enabled, otherwise the existing IDT code is chosen. Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com> Signed-off-by: Xin Li <xin3.li@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Tested-by: Shan Kang <shan.kang@intel.com> Link: https://lore.kernel.org/r/20231205105030.8698-29-xin3.li@intel.com
2024-01-31x86/fred: FRED entry/exit and dispatch codeH. Peter Anvin (Intel)
The code to actually handle kernel and event entry/exit using FRED. It is split up into two files thus: - entry_64_fred.S contains the actual entrypoints and exit code, and saves and restores registers. - entry_fred.c contains the two-level event dispatch code for FRED. The first-level dispatch is on the event type, and the second-level is on the event vector. [ bp: Fold in an allmodconfig clang build fix: https://lore.kernel.org/r/20240129064521.5168-1-xin3.li@intel.com and a CONFIG_IA32_EMULATION=n build fix: https://lore.kernel.org/r/20240127093728.1323-3-xin3.li@intel.com] Suggested-by: Thomas Gleixner <tglx@linutronix.de> Originally-by: Megha Dey <megha.dey@intel.com> Co-developed-by: Xin Li <xin3.li@intel.com> Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com> Signed-off-by: Xin Li <xin3.li@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Tested-by: Shan Kang <shan.kang@intel.com> Link: https://lore.kernel.org/r/20231209214214.2932-1-xin3.li@intel.com